The present invention relates to a LED luminaire for use in a livestock barn. The light is in such a luminaire emitted by Light Emitting Diodes (LEDs).
It is well known that lighting affects milk production. According to several studies the photoperiod can exert a positive effect on dairy performance when managed properly—see e.g. the article “Management of photoperiod in the dairy herd for improved production and health” by Dahl et al., published in J ANIM SCI 2003, 81:11-17. Long day lighting (LDL) has consistently been shown to improve milk yield during lactation. However, continuous lighting is not associated with greater milk yield, and, in fact, production between cows on natural or short day photoperiod and those under 24 hours of light does not differ.
Cows are sensitive animals and their day-and-night rhythm is of paramount importance. Particular light levels are necessary to impact the difference between day and night on the cow's body. As soon as a certain light level reaches the retina, the cow's nerves will send a signal to the hypophysis in the brain to lower the secretion of the hormone melatonin. This hormone results in sleepiness, increases the percentage of body fats, and disturbs the animal's productive capabilities. When the melatonin level decreases, another hormone, IGF-I, increases in the animal's blood. The function of the IGF-I hormone is to stimulate animal's activity and, hence, its milk production. Therefore, more light means an increase of milk production. Establishing a 24 hour cycle of 16 hours of daylight of 180 lux brightness (measured one meter above ground floor level) and 8 hours of darkness has been empirically shown to give the best results.
It has been suggested in e.g. the article “Photopigment basis for dichromatic color vision in cows, goats, and sheep” by Jacobs et al., published in Visual Neuroscience 15, 581-584 (1998), that cow eyes have a different wavelength sensitivity curve than human eyes.